Applicant claims priority from Korean patent application No. 2002-12171 filed Mar. 17, 2002.
1. Field of the Invention
The present invention relates to a vehicle suspension. More specifically, this invention is a vehicle suspension that has a bump stopper in an upper end of a shock absorber""s strut and another bump stopper on the upper end of a lower arm, which operate either separately or simultaneously, depending on the size of a load, in order to absorb or reduce shocks and vibration.
2. Description of the Related Art
Generally, a suspension connects an axle and a vehicle body in a vehicle such as a passenger car. It is designed to prevent shocks or vibration from a road surface from being transferred to the vehicle body in order to enhance passenger comfort and to keep freight stable. Such suspension consists of a chassis spring that absorbs shocks from the road surface, a shock absorber that improves ride comfort by controlling the free vibration of the chassis spring, and a stabilizer that prevents rolling of the vehicle. In addition, a spring, a bump stopper, and a stabilizer bar serve as a buffer or shock absorber in such suspension. The spring and the bump stopper serve as a buffer in both cases of a bump and a roll while the stabilizer bar serves as a buffer only in the case of a roll. In general, a front-wheel suspension has a smaller load change than a rear-wheel suspension depending on whether the vehicle is loaded or unloaded, so it adopts a linear constant spring with less changes in a spring constant. The rear-wheel suspension, however, adopts a progressive spring, in which the spring constant changes during loading and unloading, to enhance ride comfort. In addition, the bump stopper in the suspension is designed to control the maximum height of the bump. It also supplements the function of a spring to absorb shocks when an excess load from the road surface is transferred to the suspension, which is caused when the vehicle runs on an irregular or raised road. In the case of a vehicle""s turn, it controls roll of the vehicle. To this end, a conventional suspension has a bump stopper in the upper end of a shock absorber damper, or one or two bump stoppers in the upper portion of the lower arm.
The bump stopper installed in the damper or the lower arm should be able to secure endurance and satisfy the restriction of the maximum bump height in case of an excess load from the road. To this end, the bump stopper is set to have a spring constant over four times bigger than that of the shock absorber""s main spring. If the axial load is 1G in case of loading, the bump stopper is generally set to start contacting corresponding subjects when the axial load increases to 1.3G or 1.5G.
However, it is known that the conventional suspension with a stopper damper installed either in the damper or in the lower arm has several problems. First, if the bump stopper is set to start contacting at a relatively small load in order to control a roll motion in a normal turn or to secure an appropriate ride frequency within the main spring""s ordinary range, the bump stopper starts contacting the upper surface of a damper strut prematurely. As a result, shocks cannot be absorbed softly, reducing ride comfort. This phenomenon is so-called bottoming shock.
Also, with a bump stopper installed either in the shock absorber or in the lower arm, the exact timing of contacts between the stopper and the appropriate object cannot be set according to various sizes of the axial load from the road.
If the initial spring constant of the bump stopper is cut to the level the same as or one half that of the main spring to reduce the bottoming shock phenomenon, the bump stopper""s endurance is hampered, making it easily damaged or ruined.
The present invention is designed to address the aforementioned problems. The main purpose of the present invention is to provide a vehicle suspension that can effectively absorb or reduce shocks or vibration of various magnitudes from the road surface when a car runs normally or makes a turn.
The second purpose of the present invention is to provide a vehicle suspension that can absorb and reduce shocks and vibration of various magnitudes from the road surface.
The third purpose of the present invention is to provide a suspension that has a bump stopper in a shock absorber and a bump stopper in a lower arm.
The aforementioned goals can be achieved by a vehicle suspension comprising: an upper arm assembly being connected to an upper portion of a drive shaft assembly where wheels are connected; a lower arm assembly being connected to a lower bracket of said drive shaft assembly and including a bump stopper at an upper surface which starts contacting a chassis frame""s stopper bracket if a load from a road surface is the same as or more than a preset base load; a strut assembly of which a lower portion is attached to said lower arm assembly, and including a main spring located on an outer surface and a striking plate; a shock absorber with an upper mount attached to a vehicle body and a bump stopper in an upper face which starts contacting the striking plate if a load from the road surface is the same as or less than said preset base load; and a stabilizer, of which one end is connected to the lower arm assembly.
According to the present invention, the bump stoppers can absorb or reduce shock and vibration of various magnitudes transferred from the road surface when a vehicle normally runs or makes a turn, improving safety and ride comfort.